Gareth has uploaded part 2 of his wonderful geek gift guide.
PicoCricket
(Picocrocket.com, $250) If your child's interests run more towards felt and pipe cleaners than motors and gears, more CRAFT than MAKE, he might like the PicoCricket kit more than Mindstorms. Built in cooperation with LEGO, it includes a microcontroller and sensors, but it's more about embedding these technologies inside of other things (puppets and robotic plushies, kinetic sculptures, interactive lighting, etc.). In some ways, this kit is maybe more forward-looking than NXT, because it's about the disappearance of computer and robotic technologies into the fabric of our lives, and that's the future into which these kids are really growing.
